In an FMCW radar sensor (frequency modulated continuous wave), the radar signal is transmitted continuously, however, ramp modulated in its frequency. A radar sensor of this type is discussed in German patent document DE 10 2004 051 276, in which high frequency part and at least parts of the modulation device are integrated into a single semiconductor component, a so-called MMIC (monolithic microwave integrated circuit). The remaining components of the radar sensor are formed by separate analog and digital functional components, which are specially adapted to the construction and the method of operation, desired respectively, of the high frequency part.
In motor vehicles, such radar sensors are generally used in connection with driver assistance systems, for instance, for automatic ranging, for collision warning and the like. Since such systems are used not only for increasing driving comfort, but increasingly also take over safety-relevant functions, increasingly greater demands are made on the reliability of the systems, and accordingly also on the reliability of the radar sensor.